Hybrid imaging using low-dose, localizing computed tomography enhances lesion localization in renal hyperparathyroidism.

BACKGROUND Preoperative localization of parathyroid lesions is potentially beneficial in renal patients with hyperparathyroidism. The aim of this study was to determine the localizing value of hybrid single-photon emission computed tomography combined with low-dose x-ray computed tomography (SPECT/LDCT) compared with SPECT alone and whether the LDCT improved reader confidence. PATIENTS AND METHODS A retrospective study examined parathyroid scintigraphy results of patients previously referred with a diagnosis of renal hyperparathyroidism. All patients underwent planar scintigraphy using technetium-99m (Tc)-pertechnetate, which was immediately followed with Tc-sestamibi and SPECT/LDCT ∼60 min after sestamibi injection and a delayed static image to assess differential washout. Planar subtraction images were generated. Two nuclear physicians, assisted by a radiologist, reported on planar+SPECT images followed by planar+SPECT/LDCT images. RESULTS Thirty-seven patients (males: 21; females: 16) were included (mean age 39 years, range: 23.9-55.5). Mean creatinine level was 878 μmol/l (109-1839), mean corrected calcium level was 2.42 mmol/l (1.77-3.64), and median parathyroid hormone level was 156.2 pmol/l (2.4 to >201). Twenty-three patients had positive planar and SPECT results (46 lesions), six had positive planar results only, and eight had negative scintigraphy results. In the patients with positive planar and SPECT results, 35 lesions were classified as eutopic and 11 as ectopic. After the addition of LDCT, localization of five eutopic lesions (on SPECT) was amended to ectopic locations (on SPECT/LDCT), principally by identifying posteriorly situated glands. The addition of LDCT led to increased confidence in localization in all cases. CONCLUSION Compared with SPECT alone, SPECT/LDCT is beneficial in preoperative localization of lesions in renal hyperparathyroidism.